Metrics for Vehicle Density in Urban Environment

Vehicular Ad Hoc Networks (VANETs) have received a great interest either form academia and from industry since a decade because of their potential for Cooperative-Intelligent Transportation Systems (C-ITS). Then many many issues have been investigated in order to improve performances of such networks as packet delay, throughput,.. As a consequence, such systems could participate in the future to reduce accidents on the roads and traffic jams. Unicast forwarding over VANETs are usually geographic for one main reason: the nodes are dynamic, then their location change continously and the network connectivity is never stable. As a consequence, packet loss is a serious issue which has to be considered with care. Among known solutions to care this issue, we have to find appropriate metrics to measure paths to be used in order to forward packet in the network. This paper aims to propose a new metric called Link Connectivity (LC) in order to find the path with the highest connectivity between the source vehicle and the destination vehicle. Then this metrics is a basis for a unicast routing protocol over VANETs in city environment. The proposed approach is able to find the path with higher connectivity in urban environments which guarantees a high packet delivery. This metrics has been integrated into the a greedy based routing algorithm which has been developed over the simulator OMNET++ and a comparison to the GyTAR \cite{Jerbi2009}algorithm has been undertaken. We have conducted extensive simulations with different scenarios to evaluate the scalability of the approach and the robustness against frequent topology changes. As a conclusion, we have observed that this metrics has a positive impact on performance indicators as packet delivery ratio, end-to-end delay and overhead as compared to EGyTAR protocol.